Abstract: A method can be used to perform an operation on a system that includes an assembly and a vessel that includes a wall and a thermal shield. The method can include breaking a thermal connection between the assembly and the thermal shield, separating the assembly and a surface within the vessel from each other, or any combination thereof. The method can also include changing a pressure with the vessel to be closer to atmospheric pressure, heating the assembly, or any combination thereof. In one embodiment, the method can be performed while keeping a cryogenic region substantially sealed, keeping a superconducting magnet energized, or a combination thereof. In a particular embodiment, the method can be used when servicing the assembly, such as a cryocooler.

Abstract: A seat, a chair, or a combination thereof can be part of or used in conjunction with an MRI system. The seat can be designed to allow for an MRI analysis without requiring insertion of a probe into a cavity of a patient. In one embodiment, the seat and chair can be adapted for use with a cylindrical-type MRI system. The seat and chair may be used with another type of MRI system, such as an open MRI system. The pelvic region or adjacent portion of a patient can be analyzed without the patient having to lie flat.

Abstract: A cylindrical MRI system can be configured such that a patient does not have to be in a lying position during analysis. In a particular embodiment, the patient can sit during analysis. The cylindrical MRI system can be oriented such that a central axis is not parallel to the floor, and in one embodiment, is substantially perpendicular to the floor. In one embodiment, the cylindrical MRI system can be configured to allow an object to contact the patient when the patient is within the analyzing region, even when the primary magnet is at field. In another aspect, an MRI system can include a primary magnet and a gradient coil with different types of shapes. In still another aspect, an MRI system can include a gradient coil that includes a combination of portions having different shapes.

Abstract: A superconducting magnet is accessible for ramping within a cryostat by inserting flexible current leads through openings in the cryostat and pushing and twisting these leads inward until connections are made with electrical contacts provided on the superconducting magnet. For each current lead, a permanently installed channel guides the lead as it is pushed through the external opening and extends to make contact with the magnet terminal. The guide channel extends outside of the cryostat and includes an internal or external bend, whereby the overhead space required for the cryostat/magnet assembly may be reduced. After ramping, the leads are withdrawn.

Abstract: A MRI cryostat, which contains a superconducting magnet operating in a bath of liquid helium, reduces the boil-off rate of helium by intercepting most of the heat in-leakage by means of a throttle cycle (TC) refrigerator operating at a low side temperature of about 90K. The main heat exchanger for the throttle cycle refrigerator is located within or immediately adjacent to the cryostat housing and delivers cold liquid to a cold heat exchanger that is in thermal contact with an outer radiation shield, support struts, neck tube and electrical leads inside the cryostat. Heat is intercepted by the outer shield from essentially all paths between a 300K ambient and a 4K load temperature, which temperature results from liquid helium boil-off to atmosphere. A second, inner radiation shield at 35K is cooled by gaseous helium that boils from the liquid helium bath. There are no moving parts of the refrigeration system in the cryostat. Thus, vibration, noise and disturbance of the magnetic field are reduced.